US5777522AExpiredUtilityPatentIndex 73

Electronic device for controlling a reactance value for a reactive element

Assignee: MOTOROLA INCPriority: Jan 3, 1997Filed: Jan 3, 1997Granted: Jul 7, 1998

Est. expiryJan 3, 2017(expired)· nominal 20-yr term from priority

Inventors:RYBICKI MATHEW A CAVE MICHAEL D

H03L 7/099H03B 5/364H03B 2200/0062H03B 2201/0208H03B 2201/0291H03K 3/0307H03L 7/081H03B 5/32H03B 5/368H03J 2200/10

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Claims

Abstract

A capacitor (200) having an actual physical capacitance value of Cact and is coupled to an oscillator (36). The oscillation frequency of the oscillator (36) can be changed by changing the effective capacitance of the capacitor (200). The actual capacitance (Cact) of capacitor (200) can be altered to appear to be any effective capacitance (Ceff) between zero and a value much greater than Cact by using a Miller effect. In order to alter the effective capacitance of the capacitor (200), a representation of the output osculation signal (16) is provided to a frequency adjust stage (22). The frequency adjust stage either passed the signal (16) with 0° phase shift or with 180° phase shift. In addition to shifting the phase, the stage (22) will amplify or attenuate the signal (16) to result in the phase shifted and amplified/attenuated frequency adjusting signal (24). By providing the signals (16 and 24) to opposite ends of the capacitor (200), Miller affect will alter the effective capacitance of the capacitor (200) thereby altering a frequency of the oscillator (36).

Claims

exact text as granted — not AI-modified

What is claimed is: 
     
       1. An electronic device comprising: an oscillation stage capable of generating an output oscillation signal, the oscillation stage comprising an oscillation element having a first node and a second node, and a reactive element having a first node coupled to the first node of the oscillation element, and a second node of the reactive element having an actual reactance;   a frequency adjust stage having an input node for receiving a representation of the output oscillation signal, and an output node, wherein the frequency adjust stage is capable of processing the representation of the output oscillation signal to provide a frequency adjust signal at the output node, the frequency adjust signal capable of being phase shifted by one of approximately 0° and approximately 180° with respect to the representation of the output oscillation signal and being amplified; and   whereby the frequency adjust stage output node is coupled to the second node of the reactive element for changing an effective reactance of the reactive element to a reactance different from the actual reactance, the effective reactance capable of affecting a frequency of the output oscillation signal.   
     
     
       2. The electronic device of claim 1, wherein the input node of frequency adjust stage is coupled to the first node of the oscillation element for receiving the representation of the output oscillation signal. 
     
     
       3. The electronic device of claim 1, wherein the input node of frequency adjust stage is coupled to the second node of the oscillation element for receiving the representation of the output oscillation signal. 
     
     
       4. The electronic device of claim 1, wherein the frequency adjust signal is capable of being amplified at an amplification value of approximately zero. 
     
     
       5. The electronic device of claim 1, wherein the frequency adjust stage further comprising an inverter having an input node coupled to the input node of the frequency adjust stage, and an output node coupled to the output node of the frequency adjust stage. 
     
     
       6. The electronic device of claim 5, wherein the frequency adjust stage further comprising a first voltage reference terminal coupled to the inverter and a second voltage reference terminal coupled to the inverter, wherein the first voltage reference terminal and second voltage reference terminal are capable of receiving a variable potential such that during a first time period the first voltage reference terminal has a potential greater than a potential of the second voltage reference terminal, and during a second time period the second voltage reference terminal has a potential greater than the potential of the second voltage reference terminal. 
     
     
       7. The electronic device of claim 6, wherein the frequency adjust stage further comprising a buffer having an input node coupled to the input node of the frequency adjust stage, and an output node coupled to the output node of the frequency adjust stage. 
     
     
       8. The electronic device of claim 7, wherein the frequency adjust stage further comprising a resistor having a first terminal coupled to the input node of the frequency adjust stage, and a second terminal coupled to the input node of the inverter. 
     
     
       9. The electronic device of claim 8, the frequency adjust stage further comprising a power down input coupled to the input node of the inverter and the input node of the buffer, wherein the frequency adjust stage is capable of entering a low power mode when the power down input is asserted. 
     
     
       10. An electronic device comprising: an oscillation stage for providing an oscillation signal having a reactive element and an oscillator portion, wherein the reactive element has a first node coupled to the oscillator portion, and a second node;   an oscillator reference terminal coupled to the oscillation stage for providing a representation of the oscillation signal;   a first inverter having an input terminal coupled to the oscillator reference terminal, an output terminal coupled to the second node of the reactive element, a first power supply terminal coupled to receive a first voltage reference, and a second power supply terminal coupled to receive a second voltage reference; and   a buffer having an input coupled to the oscillator reference terminal for receiving an inverted representation of the oscillation signal, an output coupled to the output of the first inverter, a first power supply terminal coupled to receive the first voltage reference, and a second power supply terminal coupled to receive the second voltage reference.   
     
     
       11. The electronic device of claim 10, wherein the oscillator portion of the oscillation stage further comprises: an oscillator element having a first terminal coupled to the first terminal of the reactive element, and a second terminal;   a second inverter having a first terminal coupled to the first terminal of the oscillator element, and a second terminal coupled to the second terminal of the oscillator element; and   a resistive element having a first terminal coupled to the first terminal of the oscillator element and a second terminal coupled to the second terminal of the oscillator element.   
     
     
       12. The electronic device of claim 11 wherein the oscillator reference terminal is coupled to the first terminal of the oscillator element. 
     
     
       13. The electronic device of claim 11, wherein the oscillator reference terminal is coupled to the second terminal of the oscillator element. 
     
     
       14. The electronic device of claim 10, wherein there is a Miller effect created across the reactive element. 
     
     
       15. The electronic device of claim 14, wherein the Miller effect created across the reactive element can be controlled. 
     
     
       16. The electronic device of claim 15, wherein the Miller effect is controlled by varying at least one of the first voltage reference and the second voltage reference. 
     
     
       17. An electronic circuit comprising: an oscillation element having a first terminal which provides an first oscillation signal and a second terminal which provides a second oscillation signal;   a reactive element having a first terminal and a second terminal, wherein the first terminal is coupled to one of either the first terminal and the second terminal of the oscillation element; and   a first circuit element having a first terminal coupled to one of either the first terminal or the second terminal of the oscillation element in order to receive an input signal having an amplitude A, and a second terminal coupled to the second terminal of the reactive element, wherein the first circuit element provides an output signal to the second terminal having a phase that is approximately 0° out of phase with a signal present on the first terminal of the reactive element, and the output signal capable of being amplified to an amplitude of approximately A(n) wherein n comprises a range of 0&lt;n&lt;1, wherein a Miller effect occurs on the reactive element.   
     
     
       18. An electronic circuit comprising: an oscillation element having a first terminal which provides an first oscillation signal and a second terminal which provides a second oscillation signal;   a reactive element having a first terminal and a second terminal, wherein the first terminal is coupled to one of either the first terminal and the second terminal of the oscillation element; and   a first circuit element having a first terminal coupled to one of either the first terminal or the second terminal of the oscillation element in order to receive an input signal having an amplitude A, and a second terminal coupled to the second terminal of the reactive element, wherein the first circuit element provides an output signal to the second terminal having a phase that is approximately 180° out of phase with a signal present on the first terminal of the reactive element, and the output signal capable of being amplified to an amplitude of approximately A(n) wherein n comprises a range of 0&lt;n, wherein a Miller effect occurs on the reactive element.   
     
     
       19. An Asymmetric Digital Subscriber line system comprising: an analog to digital converter capable of receiving an analog signal comprising a reference signal, and capable of providing a digital representation of the analog signal;   a controlled oscillation stage having a control signal input terminal for receiving a control signal, and an output terminal for providing an oscillation signal, wherein the control signal is capable of controlling oscillation signal by adjusting an effective reactance of a reactive device by varying a potential on a first and second terminal of the reactive device;   a time to frequency domain converter capable of converting the digital representation of the analog signal and the oscillation signal from a time domain to a frequency domain; and   a phase detection stage coupled to the time to frequency domain converter, where in the phase detection stage is capable of generating the control signal based on a frequency domain representation of the reference signal and the oscillation signal.   
     
     
       20. The electronic device of claim 18 wherein the reactive element is a capacitor. 
     
     
       21. The electronic device of claim 20, wherein the reactive element is a non-variable capacitor. 
     
     
       22. The electronic device of claim 18 wherein the reactive element is a varactor. 
     
     
       23. The electronic device of claim 18, wherein the reactance value of the reactive element is a capacitance value. 
     
     
       24. An electronic device comprising: a first transistor of a first conductivity type having a gate coupled to an input terminal, a first current electrode coupled to a first voltage reference terminal capable of receiving a first voltage potential, a second current electrode coupled to an output terminal, and a bulk electrode coupled to a second voltage reference terminal capable of receiving a second voltage potential;   a second transistor of a second conductivity type having a gate coupled to the input terminal, a first current electrode coupled to the second current electrode of the first transistor, a second current electrode coupled to a third voltage reference terminal capable of receiving a third voltage potential, and a bulk electrode coupled to a fourth voltage reference terminal capable of receiving a fourth voltage potential;   a third transistor of a second conductivity type having a gate coupled to the input terminal, a first current electrode coupled to the first voltage reference terminal, a second current electrode coupled to the output terminal, and a bulk electrode coupled to the fourth voltage reference terminal; and   a fourth transistor of a first conductivity type having a gate coupled to the input terminal, a first current electrode coupled to the second current electrode of the third transistor, a second current electrode coupled to the third voltage reference terminal, and a bulk electrode coupled to a second voltage reference terminal.   
     
     
       25. The electronic device of claim 24 wherein the gate of the third transistor and the gate of the fourth transistor are coupled in series to the input terminal through a first inverter. 
     
     
       26. The electronic device of claim 25 further comprising a first resistor having a first terminal coupled to the gate of the first transistor, and a second terminal coupled to the output terminal. 
     
     
       27. The electronic device of claim 27 further comprising: a fifth transistor having a gate coupled to a power down terminal capable of receiving a power down signal, a first current electrode coupled to an input of the first inverter, a second current electrode coupled to the fourth voltage reference terminal, and a bulk terminal coupled to the fourth voltage reference terminal;   a second inverter having an input coupled to the power down terminal, and an output; and   a sixth transistor having a gate coupled to the output of the second inverter, a first current electrode coupled to the second voltage reference terminal, a second current electrode coupled to the gate of the first transistor, and a bulk electrode coupled to the second voltage reference terminal.   
     
     
       28. The electronic device of claim 27 further comprising a second resistor having a first terminal coupled the input of the first inverter, and a second terminal coupled to an output terminal of the second inverter. 
     
     
       29. The electronic device of claim 25, wherein the electronic device is capable of operation when the first voltage potential is one of a potential greater than the third voltage potential and a potential less than the third voltage potential. 
     
     
       30. The electronic device of claim 24, wherein the first voltage potential is substantially equal to the second voltage potential. 
     
     
       31. The electronic device of claim 24, wherein the third voltage potential is substantially equal to the fourth voltage potential.

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